In the past decade, various mobile/portable devices have been developed and produced in large quantities. For example, the use of mobile phones, tablet computers, media players and the like has become ubiquitous. Such devices are often powered by internal secondary batteries thereof, but the internal secondary batteries need to be recharged subsequently. Alternatively, such devices are directly connected to an external power supply device and powered by the external power supply device.
While most of the mobile/portable devices need to be electrically connected to or contacted with an external power supply device and powered by the external power supply device, this requirement is often impractical.
The mobile/portable device is in electric contact with the external power supply device via a connector physically inserted into the mobile/portable device and the external power supply device by a user or in other manners. Under this condition, a long wire is often required, which is often inconvenient for users. Most of the mobile/portable devices are configured with dedicated power supply devices for different power requirement. Therefore, the user must own different dedicated power supply devices for specific mobile/portable devices. The used mobile/portable devices may be powered by the internal secondary batteries thereof without wire connection between the mobile/portable device and the power supply device, but this solution still has significant disadvantages. For example, the damaged internal secondary battery needs to be recharged or replaced with an expensive new one. The internal secondary battery provided in the mobile/portable device may also greatly increase the weight of the device, and potentially increasing cost and size.
A wireless power supply device has been used for the mobile/portable device so that user experience is significantly improved. When a transmitter coil of a power transmitter device senses a magnetic field on receiver coils of power receiver devices, the power may be transmitted respectively to the receiver coils from the transmitter coil. Power delivery by magnetic induction is a well-known concept that is mainly used in transformers and has a tight coupling between a primary transmitter coil and a secondary receiver coil. The primary transmitter coil and the secondary receiver coil are spaced from and electromagnetically coupled with each other. In this way, the power transmission between them can be carried out based on electromagnetic coupling principle of the transformer.
Such configuration allows power to be transmitted between the mobile/portable device and the power supply device without wire connection or other physical electrical connection. In practice, the mobile/portable device may be placed at a position located near or on the transmitter coil so as to be recharged or powered by the transmitter coil.
Furthermore, in the above-mentioned wireless power transmission configuration, the power transmitter device may be designed to be applicable for different types of power receiver devices. More specifically, a wireless power transmission standard such as a Qi standard has been defined and is currently being developed. The power transmitter device that conforms to the Qi standard can be used for the power receiver that conforms to the Qi standard, without the need for the power transmitter device and the power receiver being made by the same manufacturer or dedicated to each other. The power transmitter device has a function of supplying appropriate power to the power receiver, for example, according to specific power consumption, based on Qi standard.